(1):

(v. i.) To play the mountebank.

(2):

(n.) One who mounts a bench or stage in the market or other public place, boasts of his skill in curing diseases, and vends medicines which he pretends are infalliable remedies; a quack doctor.

(3):

(n.) Any boastful or false pretender; a charlatan; a quack.

(4):

(v. t.) To cheat by boasting and false pretenses; to gull.